INVESTIGATING A ROLE FOR NOTCH SIGNALING IN ANGIOGENESIS

从细胞命运决定，组织模式和形态发生到人类疾病的各种过程中都涉及Notch信号。事实上，哺乳动物的四种Notch基因中有三种与癌症有关，而编码Notch3和Notch配体Jagged1的基因在两种涉及血管发育和维持缺陷的遗传性人类疾病中发生突变。此外，Jagged1在血管生成中的作用也从我们的研究中得到了证实，这些小鼠缺乏Jagged1，在胚胎发生早期死亡，表现出血管生成重塑的缺陷。有趣的是，缺乏Notch配体Delta1的动物也表现出严重的出血表型。综上所述，这些数据有力地表明Notch信号在血管生成中的作用。为了研究Notch信号在血管发育中的作用，我们将使用鸡胚绒毛膜尿囊膜（CAM）。我们的策略是通过逆转录病毒介导的表达，将Notch1或其配体Delta1和Jagged1引入CAM，激活或抑制该膜血管化过程中的Notch信号。通过分析Notch活性的丧失或增加所产生的影响将使我们能够确定Notch信号在血管生成中的作用。与Notch信号在CAM血管化过程中的作用一致，我们已经检测到Notch1， Notch2， Jagged1和Delta1在该膜发育过程中的表达，我们目前正在确定表达这些基因的CAM细胞类型。

Notch signaling has been implicated in a wide variety of processes from cell fate decisions, tissue patterning and morphogenesis to human disease. In fact, three of the four mammalian Notch genes are associated with cancer while the genes encoding Notch3 and the Notch ligand, Jagged1, are mutated in two inherited human diseases that involve defects in vascular development and maintenance. Furthermore, a role for Jagged1 in angiogenesis is emerging from our studies with mice deficient in Jagged1 that die early during embryogenesis, exhibiting defects in angiogenic remodeling. Interestingly, animals lacking the Notch ligand Delta1 also display a severe hemorrhagic phenotype. Taken together, these data strongly suggest a role for Notch signaling in angiogenesis. To investigate a role for Notch signaling in vascular development we will use the chick embryo chorioallantoic membrane (CAM). Our strategy is to introduce forms of Notch1 or its ligands, Delta1 and Jagged1 into the CAM, using retroviral-mediated expression, that will either activate or inhibit Notch signaling during vascularization of this membrane. Analysis of the effects produced through loss or gain in Notch activity will allow us to determine a role for Notch signaling in angiogenesis. Consistent with a role for Notch signaling during vascularization of the CAM, we have detected the expression of Notch1, Notch2, Jagged1 and Delta1 during development of this membrane and we are currently determining the CAM cell types that express these genes.